1. Field of the Invention
The present invention is directed to an improved protective insulating device adapted to be placed about an article to be protected from fire.
2. Description of the Prior Art
The need for means of fire proofing articles such as electrical conductors, conduits or pipes, and electrical motors so that they will withstand high temperature fires, having an open flame temperature as high as 1600.degree. to 2000.degree. F. for extended periods of time is desirable in a number of industrial applications. The petroleum industry, and particularly the refining portion of the petroleum industry, is one such industrial application where high temperature protection is desirable. Because of the extremely high flammability of products being produced, transferred and stored, protection against hydrocarbon fires which react such high temperatures referred to above for extended periods of time is essential. It is necessary that the piping and electrical systems which may be connected throughout an entire refinery or plant not ignite and thereby spread the fire throughout the entire installation. Electrical motors, pipes and cables must be made to withstand such high temperature fires for time periods on the order of fifteen to thirty minutes or more in order to provide adequate time to contain the fire. During this time period it is essential that the system remain functional in order to allow for an orderly operation or plant shutdown in order to isolate the unit wherein the fire is to be extinguished.
Typical non-flammable cable insulation such as polyvinyl chloride (PVC), neoprene or chlorinated polyethylene is unable to withstand such high temperature fires for extended periods of time. Typical electrical motor winding insulation is also unable to withstand such extreme open flame temperatures. As much of the hydrocarbon fluid is transported throughout a typical industrial plant by means of pumps which are powered by electric motors, it is mandatory that such motors be kept in operation in order to provide for continued plant operation or orderly shutdown. Further, many industrial plants employ electric motor operators which are utilized to perform various functions such as, for example, the opening and closing of valves in product lines. It is often of critical importance that electrically operated valves be closed in order to isolate an industrial fire; thus it is in turn of great importance that such motors be protected from damage and failure by the high temperatures produced by such fires. Further, hydraulically operated valves are also subject to being damaged by fire. When the insulation on the coil windings of electrical motors or electrical cables located within the plant are exposed to fire, the insulation decomposes and any chlorine present in the insulative compound is freed which combines with the humidity in the air or water, which has been used for extinguishing the fire, and forms hydrochloric acid which can penetrate concrete foundations and attack steel reinforcement.
The electrical wiring system for many industrial plants utilizes a cable tray into which a plurality of cables are placed. Such a tray increases the fire hazard over the alternate system of encasing the cables in metal conduits. Electrical junction boxes in such electrical wiring systems are another area in which a substantial fire hazard is present. In the electrical tray system, the cables are simply laid or suspended on trays throughout the plant. This system thus facilitates insulation repair of the cables since they do not have to be pulled through a conduit as in the alternative method. However, in the tray the fire hazard is increased because of the number of cables set adjacent each other as well as the possibility of combustible material being collected in the suspended trays.
Piping system in many chemical plants must be designed in order to handle corrosive and flammable fluids. Because of the corrosion resistance nature of piping fabricated from polyvinyl chloride, such piping has found wide application in the handling, pumping and storing of corrosive fluids. Where such piping is used in plants such as petroleum refineries or in the chemical industry to transport corrosive fluids, it is essential that the pipe be able to withstand high temperature flash fires and open flame temperatures of on the order of 1600.degree. to 2000.degree. F.
Simple and efficient means for protecting cables and pipes and electrical motors from high temperature fires for extended periods of time have not been completely successful. Where the cable or pipe or electrical motor is wrapped or coated and exposed to the harsh environment of the chemical plant and to outdoor weathering, asbestos wrappings and other coatings have been found to deteriorate and lose their fire protective ability. Glass fibers when used for such applications have generally demonstrated a higher strength and durability over their asbestos counterparts; however, since such glass fiber may sinter in the region of 1000.degree. F., they are not suitable for the protection against high temperature flash fires which may occur for example, in a petroleum refining plant.
In order to provide protection for the various shapes of the articles to be protected from fire such as electrical motors, fire protective means have been provided which may be applied as a viscous liquid or semisolid mixture of a flame retardent material and a solvent, such mixtures being applied by means of a spraying or troweling. Such fire protective means become solid in a relatively short period of time as the solvent evaporates. While such fire protective means may be proficient at protecting an article from fire, they are unsatisfactory for such an application because this permanence prevents periodic maintenance and examination of the motor without extensive expense in removing and then reapplying such compounds.
Industrial and other fires typically spread at ground level with their flames reaching upward, thus greater fire protection is often required at the base or bottom of an article to be protected as contrasted with its sides and top. The viscous liquid and semisolid fire protective means described above may require more than a single application in order to achieve such increased protection at the base of the article to be protected. Furthermore it is difficult to apply such prior art fire protective materials in order to provide a uniformly increased thickness of the article base.
It is an object of this invention to provide an improved fire protective insulating device. Other objectives will become apparent upon a reading of the entire specification including the drawings and claims.